Objective: Antibodies to Th/To ribonucleoprotein (anti-Th/To) have been detected almost exclusively in patients with systemic sclerosis. Therefore, we aimed to determine the prevalence of anti-Th/To in patients with localized scleroderma.
Methods: Seventy serum samples from patients with localized scleroderma were examined by RNA immunoprecipitation and indirect immunofluorescence analysis using HEp-2 cells as substrate.
Results: Three (4%) of 70 sera from patients with localized scleroderma immunoprecipitated 7-2 (Th) RNA and 8-2 (To) RNA. Indirect immunofluorescence analysis demonstrated that all the sera positive for anti-Th/To showed mainly nucleolar staining. In one patient, the coexistence of anti-histone antibody with anti-Th/To was detected by enzyme-linked immunosorbent assay for anti-histone antibody and confirmed using an absorption test with histones followed by indirect immunofluorescence analysis. Moreover, the localized scleroderma patients with anti-Th/To tended to have significantly fewer sclerotic lesions than those without.
Conclusion: Anti-Th/To is one of the serological abnormalities in localized scleroderma, and the presence of anti-Th/To may be a serological indicator of a mild form of cutaneous involvement.